i have a yellow watchman goby and pistol shrimp pair and mine eats fine but if you don't see him eating they will eat pods in your tank if they really want to eat. Are you making sure that the food gets down to the bottom for him?
If your tank is well established he may just be eating pods, etc. I only recently have seen mine eat pellets, once I took out my dottyback. I have had him for a year and he hasn't starved...